As one of the causes of global warming, the greenhouse effect by CO2 has been identified, and a countermeasure thereof is urgently required internationally from the viewpoint of protecting the global environment. Sources of CO2 emission spread over various fields of human activity where fossil fuel is burned, and demand on emission reduction of CO2 tends to increase. As a result, for power generation facilities such as a thermal power plant where a large amount of fossil fuel is used, a CO2 recovery method has been actively studied in which flue gas of a boiler is brought into contact with an amine-based absorption solution such as an aqueous amine compound solution so as to remove and recover CO2 from the flue gas.
In the related art, PTL 1 discloses an amine recovery process in which an amine compound accompanying decarbonated flue gas, from which CO2 has been absorbed and removed by gas-liquid contact with an absorption solution, is sequentially recovered in plural stages of water-washing sections that are provided for bringing the decarbonated flue gas into gas-liquid contact with a washing solution to recover the amine compound.
In addition, in the related art, PTL 2 discloses a configuration including: a cooling unit that cools decarbonated flue gas from which CO2 has been absorbed and removed by gas-liquid contact with an absorption solution; and a contact unit that brings condensate, which has been condensed in the cooling unit, into counterflow contact with the decarbonated flue gas. Further, PTL 2 discloses a configuration including a water-washing section in which an amine compound accompanying decarbonated flue gas is recovered. In this configuration, condensate, which has been condensed in a cooling tower in which flue gas is cooled before CO2 is recovered therefrom, is used as washing water.